Finding Height Maps on the Web

Mt Taranaki height map - 15m DEM from Koordinates

09/14/2012 - 06:12

This tutorial provides height maps, links to them, and talks about what to look for. It is written from the point of view of someone wanting to use them for modelling terrain in Blender, but it is relevant to modelling with other 3d packages.

Ready to go New Zealand height maps

I've converted a few height maps into the .png format. On the thumbnails below click to enlarge, then Right click >> Save Image As.

And here's a, high resolution, 1m DEM of Wellington East, try subdividing it 600 times. There are details in it that you won't see in the height maps above. You can see the cutting where the road goes through the hills into the Mirimar peninsula, the plateau formed by the airport, the wharves, the roads around the coast.

The height maps above come from two sources, Koordinates and Landcare Research. They have maps of all of New Zealand in GeoTIFF and ASCII formats, which can be opened with QGIS. These websites know height maps as Data Elevation Models (DEMs). You can download several maps at once, you can also crop an area of interest which saves on download time. Both websites allow you to choose the map projection. Just accept the default.

Terms & Conditions - My understanding is that you may use the SRTM .hgt files without restriction, please correct me if I'm wrong.

Governments and councils of many countries have height maps that you can download for free, it's just a matter of looking, or asking.

World height maps from NASA - improved by Jonathan de Ferranti

Jonathan de Ferranti has spent a lot of time improving DEMs from SRTM and other sources. He has his improved DEMs available from Viewfinder Panoramas.

Height map file formats

All height maps files are an array of numbers. The numbers are sometimes shown as colours.

0

0

1

1

0

0

2

2

4

3

3

4

0

0

0

0

What makes the formats different from each other is the range of numbers and the metadata. And what software you need to handle them. Blender requires an image format such as .png or .jpg. For other formats you will need QGIS to convert them. These other formats have metadata which says:-

how wide the map is

what scale was used

the projection method

the unit of measurement, metres or feet

the position of the map

The metadata makes it easy to join maps together. This is important because the maps are often broken up into tiles. New Zealand, which is a small island country, has a DEM that is 1.7 gigabytes in size. The DEM is accurate to 25 metres. Such a file can slow down a computer markedly. A 1 metre DEM of Wellington, NZ's capital, is .6 gigabytes in size, imagine how big the file of a continental country would be! But don't worry, in a couple of weeks the price of RAM will come down and this issue will go away :). In the mean time, tiles are good. QGIS is your friend for these special file formats. QGIS is free. In the next tutorial, Getting height Maps from QGIS, I will show you how to use it to convert DEMs into a usable format.